Michael A. Dirr is an American horticulturist and a professor of horticulture at the University of Georgia.
[1] Dirr's Georgia Plant Introduction Program has introduced over 40 new cultivars into the nursery trades.
Michael Dirr retired from the University of Georgia in October 2003.
Dirr has published over 300 scientific and popular publications and has authored seven books.
His book, Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture and Propagation and Uses has become one of the most widely adopted reference text in the education of Horticulture and Landscape Architecture.